Generally passive components, such as capacitors, resistors or inductors, are installed in a semiconductor package in order to enhance the electrical performance of a semiconductor package. Passive components are mounted on a substrate and encapsulated inside a molding compound. For example, a conventional semiconductor package with an encapsulated passive component is disclosed in U.S. Pat. No. 6,521,997 entitled “chip carrier for accommodating passive component”. Referring to FIG. 1, the semiconductor package comprises a chip carrier 10 (i.e. a substrate), a passive component 20 and a molding compound 30. The chip carrier 10 includes a core layer 11, a solder mask 12 and at least a pair of pads 13. The core layer 11 has a chip-attaching area and a trace-forming area around the chip-attaching area (not showed in the figures). The trace-forming area has a plurality of conductive traces for electrically connecting a chip on the chip-attaching area. The solder mask 12 is coated on the trace forming area. The paired pads 13 are formed on the trace-forming area. The periphery of upper surfaces and sidewalls of the paired pads 13 are covered by the solder mask 12 to be SMD pads (Solder Mask Defined pads), except the central regions of the upper surfaces of the paired pads 13 are exposed out of the openings of the solder mask 12. The solder mask 12 has a recessed portion 14 (i.e. flowing channel) between the paired pads 13. The passive component 20 is mounted on the paired pads 13 by means of the solder paste 40. Then the molding compound 30 is formed on the chip carrier 10 to encapsulate the passive component 20 and to completely fill the recessed portion 14 to prevent voids formed between the passive component 20 and the chip carrier 10. However, the pitch of the paired pads 13 must be reduced to match the size of the passive component 20, especially the passive component 20 gradually becomes smaller and smaller. Because the sidewalls of the paired pads 13 are covered by the solder mask 12 and the recessed portion 14 is formed between the paired pads 13, therefore, the width of the recessed portion 14 formed by the solder mask 12 will become narrower. Moreover, the solder paste 40 may flow into the recessed portion 14 by accident that causes bridging problem.